Optical article comprising a quarter-wave plate and method for making same

ABSTRACT

An optical item comprising an organic or mineral glass substrate ( 1 ) and a transparent polymeric material layer ( 3 ), characterized in that it comprises at least one intermediate layer ( 2 ) in direct contact with one main side of the substrate and the polymeric material layer, the intermediate layer(s) being made of particles of at least one colloidal mineral oxide and optionally of a binder, such (an) intermediate layer(s) having an initial porosity, and the initial porosity of the intermediate layer(s) being filled either by material from the polymeric material layer or by the substrate material if the latter is made in an organic glass and, optionally partly by the binder when present, so that the intermediate layer(s), after initial porosity filling, each represent a quarter waveplate with a wavelength in the range from 400 to 700 nm, preferably from 450 to 650 nm.

[0001] The present invention relates to an optical item, for example anophthalmic lens, comprising a transparent substrate made from asynthetic resin or mineral glass, particularly with a high refractiveindex (n_(D) ²⁵=1.5 or higher, preferably 1.55 or higher), at least onetransparent coating such as an anti-abrasion coating or a primer layerand an anti-abrasion coating and a quarter waveplate layer interposedbetween the substrate and the transparent coating.

[0002] Conventionally, one or more coatings are formed on the main sidesof a transparent substrate made of synthetic resin or mineral glass,such as an opthalmic lens, in order to impart to the item severaladvantageous properties such as shock resistance, abrasion resistance,reflection removal, etc.

[0003] Thus, generally, at least one side of the substrate is coatedeither directly with an abrasion resistant layer, or with a primerlayer, generally a layer for improving the shock resistance of the lens,on which an abrasion resistant layer may be applied, the primer layerimproving the anchoring of such an abrasion resistant layer on thesubstrate side. Finally, an anti-reflection coating may be applied tothe abrasion resistant layer.

[0004] Generally, the substrate and the abrasion resistant layer or theprimer layer have different refractive indices and consequentlyinterference fringes occur because of such an index difference at theinterface between the substrate and the abrasion resistant layer or theprimer layer.

[0005] U.S. Pat. No. 4,609,267 discloses a lens comprising a substratemade of a synthetic resin with a high refractive index (≧1.55), one faceof which is coated with an abrasion resistant layer of a dielectricsubstance with a refractive index different from that of the substrateand which, in order to reduce the reflection at the interface betweenthe substrate and the abrasion resistant layer, comprises at least oneanti-reflective layer of a dielectric or metallic substance appliedbetween the substrate and the abrasion resistant layer.

[0006] The abrasion resistant layer is a layer of SiO₂.

[0007] The interposed anti-reflective layer is a quarter waveplate andconsists either in a single layer of a blend of SiO₂ and aluminum oxideor two layers, one layer of SiO₂ and a second one made of a materialselected amongst ZrO₂, HfO₂, Ti₂O₃, TiO₂, Ta₂O₅, Si₃N₄, Yb₂O₃, Y₂O₃ orAl₂O₃.

[0008] Such anti-reflective and abrasion resistant layers are madethrough vacuum evaporation.

[0009] Nowadays, in order to form the abrasion resistant primer andcoating layers, varnishes are used, i.e., compositions leading to alargely organic material as opposed to layers with an essentiallymineral nature such as metal oxide and/or silicon oxide layers.

[0010] Moreover, in the industrial ophthalmic lens manufacturingprocesses, applying such varnish layers occurs by dipping in a varnishsolution or dispersion bath or through centrifuging a solution or adispersion on one side of the substrate.

[0011] If the refractive index of the varnish and that of the organicglass substrate do not match, i.e. if such refractive indices aresignificantly different, an interference fringe phenomenon also appearsat the interface between the substrate and the varnish.

[0012] An object of the present invention is therefore to provide anoptical item, such as an ophthalmic lens, comprising an organic ormineral glass substrate and at least one transparent polymeric materiallayer, such as, for example, a primer layer or an anti-abrasion coatinglayer wherein the interference fringe phenomenon linked to therefractive index difference of the substrate and the polymer materiallayer occurring at the interface between the substrate and the polymericmaterial layer is significantly mitigated. Another object of theinvention is to provide an optical item that is stable in time and moreparticularly, photodegradation resistant.

[0013] Another further object of the invention is to provide a methodfor manufacturing an optical item such as defined hereunder, beingeasily integrated into the conventional manufacturing method and which,more particularly, prevents as much as possible implementing vacuumcoating or any other processing step being a break in optical itemmanufacturing method.

[0014] The above-mentioned aims are reached according to the inventionwith an optical item, for example, an ophthalmic lens and moreparticularly a spectacle lens, comprising an organic or mineral glasssubstrate and an optically transparent polymeric material layercharacterized in that it comprises at least one intermediate layer indirect contact with one main side of the substrate and the polymericmaterial layer, the intermediate layer(s) being made of particles of atleast one colloidal mineral oxide and optionally of a binder, such (an)intermediate layer(s) having an initial porosity, and the initialporosity of the intermediate layer(s) being filled either by materialfrom the polymeric material layer or by the substrate material if thelatter is made in an organic glass and, optionally partly by the binderwhen present, so that the intermediate layer(s), after initial porosityfilling, each represent a quarter waveplate with a wavelength in therange from 400 to 700 nm, preferably from 450 to 650 nm.

[0015] The invention also relates to a method for manufacturing anoptical item such as previously defined comprising the steps of:

[0016] a) forming on at least one main surface of a transparent support,through dip coating or centrifugation in or of a sol of at least onecolloidal mineral oxide optionally containing a binder and sol drying,of at least one intermediate layer with an initial porosity; and

[0017] b) forming on such an intermediate layer either an opticallytransparent polymeric material layer or an organic glass substrate;

[0018] the initial porosity of the intermediate layer(s) being filledeither by polymeric material of the layer or by substrate materialformed at step b) and optionally, partly, by the binder of theintermediate layer(s) so that the intermediate layer(s), after initialporosity filling, each represent a quarter waveplate with a wavelengthin the range from 400 to 700 nm, preferably from 450 to 650 nm.

[0019] Generally, the initial porosity of the intermediate layer(s), inthe absence of a binder, accounts for at least 40% in volume, based onthe total volume of the intermediate layer(s).

[0020] Preferably, the porosity in the absence of a binder in theintermediate layer(s) accounts for at least 50% by volume.

[0021] When the intermediate layer(s) comprise(s) a binder, the actualporosity of such (a) layer(s), i.e. the porosity remaining taking intoaccount the volume occupied by the binder, but before filling by thepolymeric material from the previous layer accounts for, preferably,25%, more preferably 30% in volume based on the total volume of theintermediate layer.

[0022] The support on which the intermediate layer is formed may be anorganic or mineral substrate, preferably an organic glass, such as apreformed ophthalmic lens, or may be a main moulding surface of a mouldpart comprising at least one coating representing the opticallytransparent polymeric material layer designed to be applied ortransferred onto an organic or mineral glass substrate.

[0023] In the latter case, when the substrate is made of an organicglass, it may be formed in situ upon cast transfer of a liquidpolymerizable composition in the mould and polymerization and then thesubstrate material ensures the porosity filling in the mineral oxideintermediate layer.

[0024] The filling polymeric material layer has a surface force energyhigher than or equal to 20 milliJoules/m², preferably higher than orequal to 25 milliJoules/m² and more preferably, higher than or equal to30 milliJoules/m².

[0025] The surface force energy is calculated according to Owens-Wendtmethod described in the following reference: “Estimation of the surfaceforce energy of polymers” Owens D. K., Wendt R. G. (1969), J. APPL.POLYM. SCI, 13, 1741-1747.

[0026] The composition leading to the filling polymeric materialcomprises essentially one (or more) non fluorinated compound(s).

[0027] Preferably, the composition leading to the filling polymericmaterial comprises at least 80% of non fluorinated compounds based onthe total weight of the compounds forming the dry extract (1) of saidcomposition, more preferably at least 90% by weight, most preferably atleast 95% by weight and much more preferably 100% by weight.

[0028] Typically, the fluorine level (by weight) in the fillingpolymeric material is lower than 5% by weight, preferably lower than 1%by weight and more preferably 0% by weight.

[0029] The porosity of the quarter waveplate (after filling) ispreferably lower than 5%, more preferably lower than 3% and mostpreferably 0%.

[0030] After filling, the filling material contacts the substratesurface (when the filling material is not that of the substrate but thatof another layer such as the primer or antiabrasion layer) and makes itpossible to obtain the quarter waveplate adhesion on the substrate.

[0031] It is meant under dry extract according to the present inventionthe weight fraction of solid matters remaining after heating at 100° C.for 15 minutes.

[0032] When the polymeric material layer ensuring the filling of theintermediate layer porosity does not constitute the substrate, such alayer is generally formed by dip coating or centrifugation, preferablyby centrifugation.

[0033] The remainder of the disclosure refers to the appended figureswherein respectively

[0034]FIG. 1 is a schematic illustration of an embodiment of an opticalitem comprising a quarter waveplate according to the invention;

[0035]FIG. 2 is a schematic illustration of another embodiment of anoptical item comprising a quarter waveplate according to the invention;

[0036]FIG. 3 is a schematic illustration of another further embodimentof an optical item according to the invention;

[0037]FIG. 4 is a schematic illustration of an optical item comprisingtwo quarter waveplates according to the invention;

[0038]FIG. 5 is a flow chart of a method for manufacturing an opticalitem according to the invention;

[0039]FIG. 6 is a schematic illustration of a first implementation ofthe method for manufacturing an optical item according to the invention;

[0040]FIG. 7 is a schematic illustration of a second implementation ofthe method for manufacturing an optical item according to the invention;

[0041] FIGS. 8 to 18 are diagrams of the reflection as a function of thewavelength of optical items according to the invention and by way ofcomparison, of similar optical items which do not comprise quarter waveintermediate layer; and

[0042]FIG. 19 is an electronic transmission microphotography for anoptical item according to the invention.

[0043] The optical and geometrical features of a quarter waveplate aregiven by the following relationships:

n=(n _(s) ×n _(ν))^(1/2)

n.e=λ/4

[0044] wherein n is the refractive index at 25° C. for the wavelengthλ=550 nm of the quarter waveplate (wavelength corresponding to themaximal sensitiveness of the eye);

[0045] n_(s) is the refractive index at 25° C. for the wavelength λ=550nm of the substrate,

[0046] n_(ν) is the refractive index at 25° C. for the wavelength λ=550nm of the polymeric material layer directly in contact with the quarterwaveplate.

[0047] In other words, the index n of the quarter waveplate is thegeometrical mean of the material indices surrounding it.

[0048] In FIG. 1, there is schematically illustrated an optical itemaccording to the invention comprising an optically transparent substrate1, for example, in an organic glass. One of the main sides of thesubstrate 1 is coated with a layer of at least one colloidal mineraloxide with an initial porosity in the absence of a binder of at least40% by volume and with an appropriate thickness. An anti-abrasioncoating layer 3 is formed on the colloidal mineral oxide layer so as tofill the initial porosity, or the actual porosity when a binder ispresent, of the colloidal mineral oxide layer and achieve the quarterwaveplate 2.

[0049]FIG. 2 schematically illustrates an optical item differing fromthe optical item in FIG. 1 in that an anti-shock primer layer 4 isinterposed between the colloidal mineral oxide layer and theanti-abrasion coating layer 3. In such a case, the initial or actualporosity of the oxide layer is obviously filled by the primer materialfor forming the quarter waveplate 2.

[0050] With the knowledge of the refractive indices of the substraten_(s) and the anti-abrasion or primer coating n_(ν) (for example at 25°C. and for λ=550 nm), the formulas hereunder allow to determine inprinciple the thickness e and the refractive index n of the quarterwaveplate.

[0051] Thus, table I hereunder gives the thickness and refractive indexfeatures of the quarter waveplates for various substrate andanti-abrasion or primer coating layer combinations. SUBSTRATESPolycarbonate MR6 MR7 1.74 PC (MITSUI) (MITSUI) (MITSUI) Quarterwaveplate at 550 nm (n_(s) = 1590) (n_(s) = 1595) (n_(s) = 1665) (n_(s)= 1.74) PU latex (n_(s) = 1500) - Plate index λ/4 1.544 1.547 1.5801.615 Plate thickness λ/4 89 nm 89 nm 87 nm 85 nmEpoxyalkoxysilane/silica (n_(v) = 1.477) - 1.532 1.535 1.568 1.603 Plateindex λ/4 Plate thickness λ/4 90 nm 89 nm 88 nm 86 nm

[0052]FIG. 3 represents an optical item according to the inventionsimilar to that in FIG. 2, but comprising additionally ananti-reflection coating 5 formed on the anti-abrasion coating 3.

[0053]FIG. 4 represents an optical item according to the inventionsimilar to that in FIG. 1, but comprising two quarter wave intermediatelayers 2 a, 2 b. Most obviously, such a stack of two intermediate layerscan also be made with the optical items shown in FIGS. 2 and 3.

[0054] The substrates suited for the items according to the presentinvention can be any optically transparent substrate made in mineral ororganic glass, preferably in organic glass.

[0055] The plastic materials appropriate for such substrates include thehomo- and copolymers of carbonate, (meth)acrylics, thio(meth)acrylics,diethylene glycol bisallylcarbonate such as the material CR39® marketedby PPG, urethane, thiourethane, epoxide, episulfide and the combinationsthereof.

[0056] The preferred material for the substrates are polycarbonates(PC), polyurethanes (PU), polythiourethanes, (meth)acrylic andthio(meth)acrylic polymers.

[0057] Generally, the substrates have a refractive index n_(D) ²⁵ranging from 1.55 to 1.80 and preferably from 1.60 to 1.75.

[0058] The intermediate layer(s) 2 or 2 a, 2 b comprise at least acolloidal mineral oxide generally selected amongst SiO₂, TiO₂, ZrO₂,SnO₂, Sb₂O₃, Y₂O₃, Ta₂O₅ and the combinations thereof. The preferredcolloidal mineral oxides are SiO₂, TiO₂, ZrO₂, and the mixtures ofSiO₂/TiO₂ and SiO₂/ZrO₂.

[0059] The preferred colloidal silicas are those silicas prepared by theStöber method. The Stöber method is a simple and well known methodcomprising a hydrolysis and condensation of the ethyl tetrasilicate (Si(OC₂H₅)₄ or TEOS) in ethanol catalyzed by ammonia. The method allows toobtain a silica directly in ethanol, a quasi monodispersed particlepopulation, a controlable particle size and a particle surface (SiO⁻NH₄⁺).

[0060] In the case of a mixture of colloidal mineral oxides, preferablythe mixture comprises at least one high index oxide, i.e. with arefractive index n_(D) ²⁵≧1.54 and at least one low index oxide, i.e.with a refractive index n_(D) ²⁵<1.54. Preferably, the mineral oxidemixtures are binary mixtures, more particularly of a low index oxide anda high index oxide. Generally, the low index oxide/high index oxideweight ratio ranges from 20/80 to 80/20, preferably from 30/70 to 70/30and more preferably from 40/60 to 60/40.

[0061] The particle size of the mineral oxide generally ranges from 10to 80 nm, more preferably from 30 to 80 nm and most preferably from 30to 60 nm.

[0062] Particularly, the mineral oxide may be made of a mixture of smallsize particles, i.e. ranging from 10 to 15 nm, and large size particles,i.e. from 30 to 80 nm.

[0063] Typically, the layer 2 or each of the intermediate layers 2 a, 2b of colloidal mineral oxide has a thickness ranging from 60 to 100 nm,preferably from 70 to 90 nm, and more preferably from 80 to 90 nm, withthe proviso that such a thickness should be as close as possible to thetheoretical thickness of a quarter waveplate, considering the materialsbeing used for the optical item, for an optimal result of theinterference fringes being reduced.

[0064] The colloidal mineral oxide layers may optionally contain, beforefilling by the polymeric material layer, for example, from 1 to 30% byweight of at least one binder based on the dry weight of mineral oxideof the layer, and preferably from 10 to 25% and more preferably from 10to 20% by weight.

[0065] The binder is generally a polymeric material which is notprejudicial to the optical properties of the final quarter waveplate andwhich increases the cohesion and the adhesion of the mineral oxideparticles on the substrate surface.

[0066] The binders are generally materials similar to the anti-shockprimer compositions being described hereunder.

[0067] The preferred binders are polyurethane latices and (meth)acryliclatices, more particularly polyurethane latices.

[0068] As previously indicated, the or each of the intermediate layersof colloidal mineral oxide have a porosity of at least 40% by volume andpreferably in the order of 50% by volume based on the total volume ofthe layer, in the absence of a binder, and before filling by thepolymeric material of the primer or anti-abrasion coating layer.

[0069] The primer layer, when present, may be any primer layerconventionally used in the optical field and more particularly in theophthalmic field.

[0070] Typically, such primers, more particularly the anti-shockprimers, are coatings based on (meth)acrylic polymers, polyurethanes,polyesters or coatings based on epoxy/(meth)acrylate copolymers as well.

[0071] The (meth)acrylic polymer based anti-shock coatings are, amongstothers, disclosed in U.S. Pat. Nos. 5,015,523 and 5,619,288, whereas thethermoplastic and cross-linked polyurethane resin based coatings aredisclosed, amongst others, in Japanese Patents 63-1411001 and 63-87223,European Patent EP-040,411 and U.S. Pat. No. 5,316,791.

[0072] More particularly, the shock-resistant primer coating accordingto the invention may be manufactured from a poly(meth)acrylic latex,including of the core-shell type such as disclosed, for example, inFrench Patent Application FR 2,790,317, from a polyurethane latex or apolyester latex.

[0073] Particularly preferred anti-shock primer coating compositionsinclude the acrylic latex marketed under the trade name A-639 fromZeneca and the polyurethane latices marketed under the trade names W-240and W-234 from Baxenden Corporation.

[0074] Latices will be preferably selected with a particle size ≦50 nmand more preferably ≦20 nm.

[0075] Generally, after hardening, the shock-resistant primer layer hasa thickness from 0.05 to 20 μm, preferably from 0.5 to 10 μm and morepreferably from 0.6 to 6 μm. The optimal thickness generally ranges from0.5 to 2 μm.

[0076] The anti-abrasion coating may be any anti-abrasion coatingconventionally used in the optical field and, more particularly, inophthalmic optics.

[0077] By definition, an anti-abrasion coating is a coating improvingthe abrasion resistance of the finished optical item as compared with asimilar item which does not comprise the anti-abrasion coating.

[0078] The preferred anti-abrasion coatings are those obtained throughhardening of a composition containing one ore more alkoxysilane(s)(preferably one or more epoxyalkoxysilane(s)) or a hydrolyzate thereofand preferably a mineral colloidal filler, such as a colloidal oxidefiller.

[0079] According to a particular aspect, the preferred anti-abrasioncoatings are those obtained through hardening of a compositioncomprising one or more epoxyalkoxysilanes or a hydrolyzate thereof,silica and a hardening catalyst. Examples of such compositions aredisclosed in the International Application WO 94/10230 and U.S. Pat.Nos. 4,211,823, 5,015,523 as well as the European Patent 614,957.

[0080] The particularly preferred anti-abrasion coating compositions arethose comprising as main constituents an epoxyalkoxysilane such as, forexample, the γ-glycidoxypropyltrimethoxysilane (GLYMO), adialkyl-dialkoxysilane, such as, for example, the dimethyldiethoxysilane(DMDES), a colloidal silica and a catalytic amount of a hardeningcatalyst such as aluminum acetylacetonate or a hydrolyzate of suchconstituents, the balance of the composition essentially consisting insolvents conventionally used for formulating such compositions andoptionally one or more surfactants.

[0081] In order to improve the anti-abrasion coating adhesion, theanti-abrasion coating composition may optionally comprise an effectiveamount of a coupling agent, more particularly, when the coated substrateis made using the in-mould casting technique or IMC.

[0082] Such a coupling agent is typically a pre-condensed solution of anepoxyalkoxysilane and an unsaturated alkoxysilane, preferably comprisinga terminal double ethylene bonding.

[0083] Examples of epoxyalkoxysilanes are:

[0084] γ-glycidoxypropyltrimethoxysilane,

[0085] γ-glycidoxypropylpentamethyldisiloxane,

[0086] γ-glycidoxypropylmethyldiisopropenoxysilane,

[0087] (γ-glycidoxypropyl)methyldiethoxysilane,

[0088] γ-glycidoxypropyldimethoxyethoxysilane,

[0089] γ-glycidoxypropyldiisopropylethoxysilane, and

[0090] (γ-glycidoxypropyl)bis(trimethylsiloxy)methylsilane.

[0091] The preferred epoxyalkoxysilane is the(γ-glycidoxypropyl)-trimethoxysilane.

[0092] The unsaturated alkoxysilane may be a vinylsilane, anallylsilane, an acrylic or methacrylic silane.

[0093] Examples of vinylsilanes are:

[0094] vinyltris(2-methoxyethoxy)silane,

[0095] vinyltris-isobutoxysilane,

[0096] vinyltri-t-butoxysilane,

[0097] vinyltriphenoxysilane,

[0098] vinyltrimethoxysilane,

[0099] vinyltriisopropoxysilane,

[0100] vinyltriethoxysilane,

[0101] vinyltriacetoxysilane,

[0102] vinylmethyldiethoxysilane,

[0103] vinylmethyldiacetoxysilane,

[0104] vinyl-bis(trimethylsiloxy)silane and vinyldimethoxysilane.

[0105] Examples of allylsilanes include allyltrimethoxysilane,allyltriethoxysilane and allyltris(trimethylsiloxy)silane.

[0106] Examples of acrylic silanes are:

[0107] 3-acryloxypropyltris(trimethylsiloxy)silane,

[0108] 3-acryloxypropyltrimethoxysilane,

[0109] acryloxypropylmethyldimethoxysilane,

[0110] 3-acryloxypropylmethylbis(trimethylsiloxy)silane,

[0111] 3-acryloxypropyldimethylmethoxysilane, and

[0112] n-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane.

[0113] Examples of methacrylic silanes are:

[0114] 3-methacryloxypropyltris(vinyldimethoxylsiloxy)silane,

[0115] 3-methacryloxypropyltris(trimethylsiloxy)silane,

[0116] 3-methacryloxypropyltris(methoxyethoxy)silane,

[0117] 3-methacryloxypropyltrimethoxylsilane,

[0118] 3-methacryloxypropylpentamethyldisiloxane,

[0119] 3-methacryloxypropylmethyldimethoxysilane,

[0120] 3-methacryloxypropylmethyldiethoxysilane,

[0121] 3-methacryloxypropyldimethylmethoxysilane,

[0122] 3-methacryloxypropyldimethylethoxysilane,

[0123] 3-methacryloxypropenyltrimethoxysilane, and

[0124] 3-methacryloxypropylbis(trimethylsiloxy)methylsilane.

[0125] The preferred silane is the acryloxypropyltrimethoxysilane.

[0126] Typically, the amount of coupling agent introduced into theanti-abrasion coating composition accounts for 0.1 to 15% by weight ofthe total weight of the composition, preferably from 1 to 10% by weight.

[0127] The anti-abrasion coating thickness, after hardening, usuallyranges from 1 to 15 μm, preferably from 2 to 6 μm.

[0128] The anti-shock primer and anti-abrasion coating compositions maybe hardened thermally and/or through radiation, preferably thermally.

[0129] Most obviously, as previously indicated, the material of theprimer layer or of the anti-abrasion coating layer should penetrate intoand fill the porosity of the colloidal mineral oxide intermediate layer.

[0130] As will be seen hereunder, the anti-shock primer andanti-abrasion coating layers are preferably formed through dip coatingor centrifugation. Therefore, the compositions for forming such layersare preferably sol-gel compositions.

[0131] The optical item according to the invention may optionallycomprise an anti-reflection coating formed on the anti-abrasion coatinglayer.

[0132] The anti-reflection coating may be any anti-reflection coatingconventionally used in the optical field, more particularly, in theophthalmic optic field.

[0133] By way of an example, the anti-reflection coating may consist ina mono- or multilayer film, dielectric materials such as SiO, SiO₂,Si₃N₄, TiO₂, ZrO₂, Al₂O₃, MgF₂ or Ta₂O₅ or the mixtures thereof.

[0134] It is thereby possible to prevent a reflection from occurring atthe lens-air interface.

[0135] Such an anti-reflection coating is generally applied throughvacuum coating according to one of the following techniques:

[0136] through evaporation, optionally ionic beam assisted,

[0137] through vaporisation by ion beam,

[0138] through sputtering,

[0139] through chemical plasma-aided coating in vapour phase.

[0140] Besides to the vacuum coating, it can also be contemplated toapply a mineral layer through a sol-gel route (for example from atetraethoxy-silane hydrolyzate).

[0141] In the case where the film comprises one single layer, theoptical thickness thereof should be equal to λ/4 (λ is a wavelengthranging from 450 to 650 nm).

[0142] In the case of a multi-layer film comprising three layers, acombination may be used, corresponding to respective optical thicknessesof either λ/4, λ/2, λ/4 or λ/4, λ/4, λ/4.

[0143] An equivalent film can moreover be used, formed by more layers,instead of any number of the layers being part of the threeabove-mentioned layers.

[0144]FIG. 5 is a block diagram of the main steps of an optical itemmanufacturing process according to the present invention.

[0145] The surface of the bare substrate made of an organic or mineralglass, for example, an opthalmic lens, is first treated through dippinginto a 5% soda solution under heat, for example at 50° C. (3 minutes),followed by water and alcohol rinsing.

[0146] This is then followed by dipping in a colloidal mineral oxide solor sol centrifugation, preferably through dip coating, to coat thesubstrate treated surface with a colloidal mineral oxide layer.

[0147] In the case of a dip coating, the applied thickness depends onthe sol dry matter content, on the particle size and on the unwittingrate (Landau-Levich law). Therefore, knowing the sol composition, theparticle size, the refractive indices of the substrate and of the primeror anti-abrasion coating, one can determine the desired thickness forthe colloidal mineral oxide layer and the unwetting rate appropriate forobtaining the desired thickness.

[0148] After the applied layer has been dried, a porous colloidalmineral oxide layer is obtained having the desired thickness. The layerporosity is an essential factor and should be at least 40% by volume,preferably at least 50% by volume in the absence of a binder and atleast 25%, preferably at least 30% by volume, in the presence of abinder. The porosity of the layers can be calculated from the refractiveindices of the ellipsometry measured layers.

[0149] Drying the layer after application may occur at a temperatureranging from 20 to 130° C., preferably from 20° C. to 120° C.

[0150] Preferably, drying occurs at room temperature (20-25° C.).

[0151] In the Case of a Layer Which Does Not Comprise a Binder

[0152] The porosity of the porous colloidal mineral oxide layer is asfollows: $p = \frac{Vp}{{Vc} + {Vp}}$

[0153] wherein Vp is the volume of the pores contained in the layer andVc is the volume occupied by the mineral oxide in the layer.

[0154] The porosity p of the layer is here equal to the porosity in theabsence of a binder.

[0155] The value of porosity p is obtained from the refractive indices

[0156] n (measured by ellipsometry) which is the refractive index of theporous mineral layer,

[0157] n_(c) which is the mean refractive index of the mineral oxideparticles (optionally mixed if various oxides are used),

[0158] and from the relationship:

n ² =p+n _(c) ²(1−p)

[0159] wherein p is the pore volume fraction, assuming that the poresare filled with air and 1−p is the mineral oxide volume fraction.

[0160] The refractive indices are determined at 25° C. at a 632 nmwavelength.

[0161] In the Case of a Layer Containing a Binder

[0162] The porosity p of the layer is calculated from the followingrelationships

n ² =p+x _(c) n _(c) ² +x _(l) n ₈₀ ²  (1)

[0163] wherein:

[0164] n is the refractive index of the porous mineral oxide layer,

[0165] p is the porosity of the ${{layer} = \frac{Vp}{{Vtotal}\quad}},$

[0166] x_(c) represents the mineral oxide volume fraction in the layer${x_{c} = \frac{Vc}{{Vtotal}\quad}},$

[0167] x_(l) represents the binder volume fraction in the layer${x_{l} = \frac{Vl}{{Vtotal}\quad}},$

[0168] Vp, Vc, Vl, Vtotal respectively represent the volume occupied bythe pores (air), the mineral oxide, the binder and the entire layer,

[0169] n_(c) is the mean refractive index of the mineral oxideparticles,

[0170] n1 is the refractive index of the binder:

p+x _(l) +x _(c)=1  (2)

[0171] $\begin{matrix}{\frac{x_{\lambda}}{x_{c}} = {\frac{m_{\lambda}}{m_{c}} \times \left( \frac{c}{l} \right)}} & (3)\end{matrix}$

[0172] dc is the density of the mineral oxide,

[0173] dl is the density of the binder,

[0174] m_(l) is the binder dry mass in the layer, and

[0175] m_(c) is the mineral oxide dry mass in the layer.

[0176] The porosity in the absence of a binder is by definitionp′=p+x_(l), i.e. the porosity that the layer would have if the bindervolume were occupied by air.

[0177] The values of p and p′ are obtained by measuring nellipsometrically, the indices n_(c) and n_(l) being additionally knownand the

[0178] The various refractive indices are determined at 25° C. at the632 nm wavelength.

[0179] In a first embodiment of the method, the anti-abrasion coatingmaterial is then dip coated (or coated through centrifugation), thendried, m_(λ)/m_(c) ratio being experimentally determined. for example inan oven at 75° C., for about 210 seconds and finally, post-hardened at100° C. for 3 hours, so as to obtain the item according to theinvention.

[0180] Alternatively, after the porous mineral oxide layer has beenformed, an anti-shock primer composition layer is dip coated (or coatedthrough centrifugation), followed by drying, for example in an oven at85° C., then the anti-abrasion coating occurs as hereinabove.

[0181] Finally, optionally, an anti-reflection coating can beconventionally applied on the anti-abrasion coating.

[0182]FIG. 6 is a schematic illustration of the quarter waveplatemanufacture according to the invention by transfer onto a preform.

[0183] As shown in FIG. 6, an intermediate layer 2 of colloidal mineraloxide optionally containing a binder is formed, preferably throughcentrifugation or dip coating on one side of a preform 1, preferablymade in an organic glass.

[0184] On a mould surface 6, preferably a flexible mould, are formed, inthe following order, a conventional anti-reflection coating layer 5, ananti-abrasion coating layer 4 and a primer layer 3. Preferably, theanti-reflection coating layer 5, the anti-abrasion coating layer 4 andthe primer coating layer 3 are dried and/or hardened, at leastpartially.

[0185] Then, an adequate amount of an adhesive material is coated eitheron the intermediate layer 2 or on the surface of the primer layer 3,preferably, the intermediate layer 2, then the preform 1 carrying theintermediate layer 2 is pressed against all the layers 3, 4 and 5,carried by the mould 6.

[0186] After the adhesive has been hardened, the mould 6 is removed soas to obtain a lens according to the invention.

[0187] The porosity of the intermediate layer 2 is then filled with theadhesive 7 forming the polymeric material layer in direct contact withthe intermediate layer 2.

[0188] In such case, the adhesive layer 7 ensures the adhesion of thestack 3, 4, 5 with the intermediate layer 2, being itself bonded withthe substrate 1.

[0189] Such an adhesive 7 may be applied on the intermediate layer 2carried by the preform 1 through centrifugation or dip coating type oron the last layer of the stack or also injected between the preform 1carrying the intermediate layer 2 and the stack carried by the flexiblemould 6.

[0190] The coating of the adhesive on the intermediate layer 2 carriedby the preform 1 is the preferred embodiment.

[0191] Preferably, the adhesive 7 is a radiation hardenable organicmaterial, for example, through UV radiation.

[0192] If the viscosity of the adhesive 7 is high, it is possible toheat the latter so as to reduce the viscosity and allow for apenetration and, therefore an optimum filling of the intermediate layer2. The heating temperature should not be too high in order to avoid athermal damage of the anti-reflection stack 5.

[0193] The quarter waveplate 2 formed prevents the interference fringes,more particularly when the refractive index difference between thesubstrate 1 and the material constituting the adhesive 7 is high. (Inthe most frequent case, it is the substrate 1 which has a highrefractive index and the adhesive 7 which has a low refractive index).

[0194] The adjacent layer 4 higher than the adhesive layer 7 formed isgenerally an anti-shock primer layer.

[0195] The case can however be contemplated where the composition of thematerial constituting the adhesive 7 is itself formulated so as to haveanti-shock properties.

[0196] In such a case, the adhesive layer 7 also plays the part of ananti-shock primer and is then directly adjacent to the anti-abrasioncoating layer 4.

[0197] Such an adhesive 7 can be made of the material disclosed in U.S.Pat. No. 5,619,288 (UV hardenable acrylates).

[0198] In FIG. 6, the quarter waveplate 2 is shown from the rear of thepreform. It might as well be made similarly from the front side.

[0199] However, for the front side, the quarter waveplate 2 ispreferably made according to the method described in relation with FIG.5.

[0200] The mould 6 may be stiff or flexible, but is preferably flexible.

[0201] Using a stiff mould is not recommended as it requires a largenumber of moulds each having a geometry surface defined so as to matchwith that of the preform.

[0202] On the contrary, when a flexible mould is used, having a singlemould is satisfactory, with a surface the geometry of which generallymatches that of the surface of the preform, i.e. a convex or a concaveshape, on which the transfer is performed.

[0203] The mould may be in any appropriate material, in particular, aplastic material, for example, polycarbonate.

[0204] The flexible mould typically has a thickness ranging from 0.3 to5 mm. Preferably, it is made in polycarbonate and has a thicknessranging from 0.5 to 1 mm.

[0205]FIG. 7 is a schematic illustration of the manufacture of a quarterwaveplate according to the invention using the so-called IMC method.

[0206] On an appropriate surface of a first part of the mould 10 a of atwo-part mould conventional for manufacturing an ophthalmic lens,successively in the indicated order, are conventionally formed a highercoating 6 with hydrophobic properties, a multi-layer anti-reflectioncoating 5, an anti-abrasion hard coating 4 and an anti-shock primerlayer 3.

[0207] On the surface of the primer layer 3 are formed, preferablythrough centrifugation or dip coating, an intermediate layer ofcolloidal mineral oxide with the required thickness and porosity.

[0208] After the two parts of the mould 10 a, 10 b have been assembledusing an adhesive seal 11, a liquid monomer composition is injected intothe mould cavity.

[0209] After hardening of the monomer composition, so as to form thesubstrat 1, and releasing, an item according to the invention isobtained.

[0210] In that case, the porosity of the intermediate layer 2 is filledby the material constituting the substrate 1.

[0211] The appropriate monomer compositions are any compositionsconventionally used for manufacturing optical items, more particularly,ophthalmic lenses.

[0212] In FIG. 7, the various layers are formed on the front side of theitem, but might as well be formed similarly on both sides of the finalglass.

[0213] In the following examples, unless otherwise specified, all thepercentages and parts are expressed by weight.

[0214] The colloid ratios in the various examples are expressed in drymatter weight.

[0215] The materials used in the examples are as follows

[0216] 1) Substrate

[0217] polycarbonate (PC): bisphenol A homopolycarbonate marketed byTeijin or General Electric,

[0218] thermohardenable polythiourethane—index n_(D) ²⁵=1.6: MR6marketed by MITSUI,

[0219] thermohardenable polythiourethane—index n_(D) ²⁵=1.67: MR7marketed by MITSUI,

[0220] polyepisulfide—index n_(D) ²⁵ =1.74: marketed by MITSUI,

[0221] mineral glass: white Stigmal Essilor—index n_(D) ²⁵=1.807.

[0222] 2) Colloidal Mineral Oxide Mean refractive Diameter index of theof the particles particules n_(c) (nm) pH Silica - SiO₂ MA-ST (Nissan)1.48 10-12 3-4 Stöber 176 1.48 74 6.5 Stöber 229 1.48 71 6.5 Ludox AS30(Dupont) 1.48 13-14 9.6 Mean refractive Diameter of index of the theparticles Titanium dioxide TiO₂ 1130 F2 (CCIC) 2.05  7-15 4-6 1120 ZS95A8 (CCIC) 1.92  6-10 3-6 Mean refractive Diameter of index of the theparticles Zircon-ZrO₂ ZSL20N DAICHI KIGENSO 2 ˜50 nm 3  

[0223]3) Primer

[0224] W 234 polyurethane latex from Baxenden

[0225] Butylacrylate/methylmethacrylate latex (ABu/MMA) disclosed inPatent Application FR 2,790,317.

[0226] 4) Anti-Abrasion Coating

[0227] The anti-abrasion coating composition is prepared adding dropwise42.9 parts of 0.1N hydrochloric acid to a solution containing 135.7parts of γ-glycidoxypropyltriethoxysilane (GLYMO) and 49 parts ofdimethyl-diethoxysilane (DMDES).

[0228] The hydrolyzed solution is added for 24 hours at roomtemperature, followed then by the addition of 8.8 parts of aluminumacetylacetonate, 26.5 parts of ethylcellulose, 400 parts of 30%colloidal silica in methanol and 157 parts of methanol.

[0229] A small amount of surfactant is then added. The theoretical dryextract of the composition approximately contains 10% of dry matter fromthe hydrolyzed DMDES.

[0230] 5) Anti-Reflection Coating

[0231] The anti-reflection coating, when present, is formed throughconventional vacuum coating of the following successive layers Opticalthickness Material (nm) First layer coated ZrO₂ 55 Second layer coatedSiO₂ 30 Third layer coated ZrO₂ 160 Fourth layer coated SiO₂ 120 (toplayer)

[0232] The optical thicknesses are given for λ=550 nm.

[0233] In all the examples, the indicated porosities p or p′ are initialporosities before filling.

EXAMPLE 1 AND COMPARATIVE EXAMPLES C1 AND C2

[0234] On one surface of a polythiourethane MR6 substrate, preliminarilytreated by a soda solution as previously described, through dip coatingin a 3% solution in methanol of a mixture 30/70 by weight of silica(MA-ST) and TiO₂ (1130F2), a colloidal mineral oxide layer is formed.After drying, the features of the mineral oxide layer are as follows

[0235] thickness: 63 nm

[0236] refractive index: 1.385

[0237] porosity p=42%.

[0238] This is followed successively, through dip coating, in theconditions as indicated hereinabove, by the formation of an anti-shockprimer layer (W234) and an anti-abrasion coating layer.

[0239] The thickness of the primer layer is approximately 1 μm and thatof the anti-abrasion coating is approximately 3.5 μm (example 1).

[0240] By way of comparison, on a surface of two MR6 substrates, throughdip coating and in the same conditions, are formed an anti-abrasion hardcoating layer (polysiloxane) with a refractive index of 1.6 adapted tothat of the substrate (comparative example C1) on the one hand and astack of a primer layer and an anti-abrasion hard coating similar tothat of example 1 (comparative example C2).

[0241] The diagrams in FIG. 8 are reflection diagrams as a function ofthe wavelength of the coated substrates.

[0242] It can be seen that the mean reflection level of the adaptedindex system (C1) is higher than that of the non adapted systems(examples 1 and C2).

[0243] It is also to be noted that the flute amplitude is stronglyreduced in the system from example 1 (interposed quarter waveplate)compared with the system in the comparative example C2.

EXAMPLES 2 TO 4 AND COMPARATIVE EXAMPLE C3

[0244] The example 1 is repeated, but using a polycarbonate substrateLexan® (General Electric) and the following colloidal mineral oxidesols: Example n° Mineral oxide sol 2 SiO₂ MA-ST/TiO₂ Z 1130F 70/30 at 3%in MeOH 3 SiO₂ Ludox AS 30/TiO₂ Z 1130F 70/30 at 3% in EtOH 4 SiO₂MA-ST/TiO₂ Z 1120 ZS 95 A8 50/50 at 3% in MeOH

[0245] The thicknesses, indices and porosities of the mineral oxidelayers obtained are as follows: Thickness of mineral oxide Example n°layer (nm) Index n Porosity p 2 63 1.385 42% 3 65 1.375 43% 4 62 1.32952%

[0246] By way of a comparison (comparative example C3), directly on apolycarbonate similar substrate are directly formed primer andanti-abrasion coating layers, similar to those from example 1 (W 234 PUprimer from Baxenden and anti-abrasion coating as defined hereabove).

[0247] The results of the reflection as a function of the wavelength arerepresented by the diagram in FIG. 9.

EXAMPLES 5 TO 7

[0248] Example 2 is repeated, but incorporating to the mineral oxide sola binder in such an amount that the sol dry extract contains 10%, 20%and 30% of the binder. The binder being used is W-234 PU latex fromBaxenden and the percentage of incorporated binder is expressed byweight based on the total dry weight of the sol mineral oxide. The solcompositions layers of the mineral oxide layer obtained are given in thetable hereunder: Thickness Ex- of the am- Mineral oxide sol mineralRefrac- Poros- Poros- ple Binder oxide tive ity ity n° Mineral oxide(%)* layer (nm) index n (%) P (%) p′ 5 SiO₂ MA-ST/ 10 67 1.343 46 57TiO₂ 1130F2 70/30at 2% in EtOH 6 SiO₂ MA-ST/ 20 74 1.378 38 59 TiO₂1130F2 70/30at 1.6% in EtOH 7 SiO₂ MA-ST/ 30 60 1.412 28 59 TiO₂ 1130F270/30at 1.5% in EtOH

[0249] The results of the reflection as a function of the wavelength aregiven by the diagrams in FIGS. 10 and 11.

[0250] In FIG. 10, the results of the reflection from example 5 aredirectly compared with those of the comparative example C3 and example2.

EXAMPLES 8 TO 10 AND COMPARATIVE EXAMPLE C4

[0251] Example 1 is repeated, but using a MR7 substrate and using thefollowing mineral oxide sols: Thickness Ex- of the am- Mineral oxide solmineral Refrac- Poros- Poros- ple Binder oxide tive ity ity n° Mineraloxide (%)* layer (nm) index n (%) P (%) p′ 8 SiO₂ MA-ST/ 20 72 1.410 3557 TiO₂ 1130F2 60/40at 1.6% in EtOH 9 SiO₂ MA-ST/ 20 73 1.440 34 57 TiO₂1130F2 50/50at 1.6% in EtOH 10 SiO₂ MA-ST/ 20 61 1.470 32 57 TiO₂ 1130F240/60at 1.6% in EtOH

[0252] By way of a comparative example C4, a MR7 substrate is alsoprepared coated with the primer layer and the anti-abrasion coatinglayer.

[0253] The results of the reflection measurement as a function of thewavelength are given by the diagrams in FIG. 12.

EXAMPLES 11 TO 13 AND COMPARATIVE EXAMPLE C5

[0254] Example 1 is repeated, but using a mineral glass substrate andusing the following mineral oxide sols: Thickness Ex- of the am- Mineraloxide sol mineral Refrac- Poros- Poros- ple Binder oxide tive ity ity n°Mineral oxide (%)* layer (nm) index n (%) P (%) p′ 11 SiO₂ MA-ST/ 20 731.440 34 57 TiO₂ 1130F2 50/50at 1.6% in EtOH 12 SiO₂ MA-ST/ 20 61 1.47032 57 TiO₂ 1130F2 40/60at 1.6% in EtOH 13 SiO₂ MA-ST/ 20 60 1.506 31 57TiO₂ 1130F2 30/70at 1.6% in EtOH

[0255] By way of a comparative example C5, a mineral substrate is alsoprepared directly coated with the primer layer and the anti-abrasioncoating layer.

[0256] The results of the reflection measurements as a function of thewavelength are given by the diagrams in FIG. 13.

EXAMPLES 14 TO 19 AND COMPARATIVE EXAMPLES C6 and C7

[0257] The same procedure is used as in example 1, but using thesubstrates, mineral oxide sols and primers as mentioned in the tablehereunder: Mineral oxide layer Example Thickness n° Substrate Mineraloxide sol 176 (nm) Index P (%) Primer 14 MR7 SiO₂ Stöber 176/ZrO₂ ZSL 831.284 67 PUW234 20N 30/70 at 2% in EtOH Latex 15 PC SiO₂ Stöber 176/ZrO₂ZSL 115 1.289 60 ABu/MMA 20N 50/50 at 2% in EtOH Latex 16 MR6 SiO₂Stöber 176/ZrO₂ ZSL 115 1.289 60 ABu/MMA 20N 50/50 at 2% in EtOH Latex17 MR7 SiO₂ Stöber 229/ZrO₂ ZSL 90 1.309 64 PUW 234 20N 30/70 at 2.5% inEtOH Latex 18 MR7 SiO₂ Stöber 229/ZrO₂ ZSL 103 1.328 61 With no 20N30/70 at 2.5% in EtOH primer 19 MR7 SiO₂ Stöber 229/ZrO₂ ZSL 103 1.32861 ABu/MMA 20N 30/70 at 2.5% in EtOH Latex C6 PC — ABu/MMA Latex C7 MR6— ABu/MMA Latex

[0258] The reflection results as a function of the wavelength are shownin FIGS. 14 to 15.

[0259]FIG. 19 is a microphotograph of the coated item from example 17.

EXAMPLES 20 TO 22 AND COMPARATIVE EXAMPLE C8

[0260] The examples hereunder illustrate the use of mineral oxide duallayers.

[0261] Each of such mineral oxide dual layers is formed through dipcoating as in example 1. The primer and anti-abrasion coatings areidentical to those in example 1 and manufactured similarly. Thesubstrates and mineral oxide sols used are given in the table hereunder.First layer Exam- Thick- Second layer ple ness Porosity ThicknessPorosity n°1 Substrate Mineral oxide sol (nm) Index (%) Mineral oxidesol (nm) Index (%) 20 MR7 SiO₂ Stöber 176/ZrO₂ ZSL 20N 88 1.346 63 SiO₂Stöber 176/ZrO₂ 115 1.289 59 20/80 at 2% in ethanol ZSL 20N 50/50 at 2%in ethanol 21 Polyepisulfide SiO₂ Stöber 176/ZrO₂ ZSL 20N 76 1.336 68SiO₂ Stöber 176/ZrO₂ 100 1.254 65 n = 1.74 13/87 at 2% in ethanol ZSL20N 50/50 at 2% in ethanol

[0262] An item is also manufactured comprising a single mineral oxidelayer according to the invention using the same procedure as in example1, using the substrate and the mineral oxide sol hereunder and the sameprimer and anti-abrasion coatings as in example 1. Thickness Example ofthe layer Porosity n° Mineral oxide sol (nm) Index (%) 22 SiO₂ Stöber176/ZrO₂ ZSL 88 1.346 63 20N 20/80at . . .

[0263] By way of a comparison (comparative example C8), a similarsubstrate (n=1.74) has been directly coated with the primer andanti-abrasion coatings.

[0264] The reflection results as a function of the wavelength are givenby the diagrams in FIGS. 17 and 18.

1. An optical item comprising an organic or mineral glass substrate anda transparent polymeric material layer characterized in that itcomprises at least one intermediate layer in direct contact with onemain side of the substrate and the polymeric material layer, theintermediate layer(s) being made of particles of at least one colloidalmineral oxide and optionally of a binder, such (an) intermediatelayer(s) having an initial porosity, and the initial porosity of theintermediate layer(s) being filled either by material from the polymericmaterial layer or by the substrate material if the latter is made inorganic glass and, optionally partly by the binder when present, so thatthe intermediate layer(s), after initial porosity filling, eachrepresent a quarter waveplate with a wavelength in the range from 400 to700 nm, preferably from 450 to 650 nm.
 2. An optical item according toclaim 1, characterized in that the porosity in the absence of a binderof the intermediate layer(s) is at least 40% by volume, preferably atleast 50% by volume.
 3. An optical item according to claim 2,characterized in that, in the presence of a binder and before filling,the intermediate layer has a porosity of at least 25%, preferably atleast 30% by volume.
 4. An optical item according to any one of claims 1to 3, characterized in that the particle size of the colloidal mineraloxide(s) ranges from 10 to 80 nm, preferably from 30 to 80 and morepreferably from 30 to 60 nm.
 5. An optical item according to any one ofclaims 1 to 4, characterized in that the binder accounts up to 30%,preferably up to 25%, more preferably from 10 to 20% by weight based onthe total weight of dry mineral oxide of the intermediate layer(s). 6.An optical item according to any one of preceding claims, characterizedin that the binder is a polyurethane latex.
 7. An optical item accordingto any one of preceding claims, characterized in that the colloidalmineral oxide is selected amongst SiO₂, TiO₂, ZrO₂, SnO₂, Sb₂O₃,Y₂O₃,Ta₂O₅ and the mixtures thereof.
 8. An optical item according to claim 7,characterized in that the intermediate layer(s) comprise(s) a mixture ofat least one low index colloidal mineral oxide (n_(D) ²⁵<1.54) and atleast one high index colloidal mineral oxide (n_(D) ²⁵≧1.54).
 9. Anoptical item according to claim 8, characterized in. that the low indexcolloidal mineral oxide /high index mineral oxide weight ratio rangesfrom 30/70 to 70/30.
 10. An optical item according to claim 8 or 9,characterized in that the colloidal mineral oxide mixture is a SiO₂ andTiO₂ mixture or a SiO₂ and ZrO₂ mixture.
 11. An optical item accordingto any one of preceding claims, characterized in that it comprises twointermediate layers.
 12. An optical item according to any one ofpreceding claims, characterized in that the organic glass substrate isselected amongst the diethyleneglycol bis(allylcarbonate) polymers andcopolymers, homo- and copolycarbonates, poly(meth)acrylates,polythio(meth)acrylates, polyurethanes, polythiourethanes, polyepoxydes,polyepisulfides and the combinations thereof.
 13. An optical itemaccording to any one of preceding claims, characterized in that thesubstrate has a n_(D) ²⁵ refractive index ranging from 1.55 to 1.80,preferably from 1.60 to 1.75.
 14. An item according to any one ofpreceding claims, characterized in that the polymeric material layer isa shock resistant primer layer.
 15. An item according to claim 14,characterized in that the primer is a (meth)acrylic polymer,thio(meth)acrylic polymer, polyester, polyurethane, polythiourethanebased material or the combinations thereof.
 16. An item according toclaim 15, characterized in that the primer material is apoly(meth)acrylic or a polyurethane latex.
 17. An item according to anyone of claims 1 to 13, characterized in that the polymeric materiallayer is an anti-abrasion coating layer.
 18. An item according to claim17, characterized in that the anti-abrasion coating results from thehardening of a composition comprising, as main constituents, an epoxyalkoxysilane, a dialkyldialkoxysilane and colloidal silica or ahydrolyzate of such constituents.
 19. An item according to any one ofclaims 14 to 16, characterized in that it comprises an anti-abrasioncoating applied on the shock-resistant primer layer.
 20. An itemaccording to any one of claims 17 to 19, characterized in that itcomprises an anti-reflection coating formed on the anti-abrasioncoating.
 21. An optical item according to any one of claims 1 to 20,characterized in that the item is an ophthalmic lens, more particularly,a spectacle lens.
 22. A method for manufacturing an optical item,characterized in that it comprises the steps of: a) forming on at leastone main surface of a support, through coating of at least one colloidalmineral oxide and optionally a binder, at least one intermediate layerof at least one colloidal mineral oxide with an initial porosity; and b)forming on the intermediate layer(s) either an optically transparentpolymeric material layer or an organic glass substrate; c) the initialporosity of the intermediate layer(s) being filled by polymeric materialof the layer or by substrate material formed at step b) and optionally,partly, by the binder so that the intermediate layer(s), after initialporosity filling, each represent a quarter waveplate in the range from400 to 700 nm, preferably 450 to 650 nm.
 23. A method according to claim22, characterized in that the support is an organic or mineral glasssubstrate.
 24. A method according to claim 22, characterized in that thesupport is a main moulding surface of a mould part comprising at least acoating representing the layer of optically transparent polymericmaterial, and the initial porosity of the intermediate layer(s) isfilled by material from the organic glass substrate.
 25. A methodaccording to claim 24, characterized in that the substrate is formedthrough casting a liquid polymerisable composition in the mould andpolymerisation of the composition.
 26. A method according to claim 23,characterized in that it comprises prior to step (a) a substratetreatment by a basic solution.
 27. A method according to any one ofclaims 22 to 26, characterized in that the initial porosity of theintermediate layer(s), in the absence of a binder, is at least 40% byvolume.
 28. A method according to any one of claims 22 to 26,characterized in that the porosity in the absence of a binder from theintermediate layer(s) is at least 50% by volume.
 29. A method accordingto any one of claims 22 to 28, characterized in that the particle sizeof the colloidal mineral oxide(s) ranges from 10 to 80 nm, preferablyfrom 30 to 80 and more preferably from 30 to 60 nm.
 30. A methodaccording to any one of claims 22 to 29, characterized in that thebinder accounts up to 30%, preferably up to 25%, more preferably from 10to 20% by weight, based on the total weight of dry mineral oxide of theintermediate layer(s).
 31. A method according to any one of claims 22 to30, characterized in that the binder is a polyurethane latex.
 32. Amethod according to any one of claims 22 to 31, characterized in thatcolloidal mineral oxide is selected amongst SiO₂, TiO₂, ZrO₂, SnO₂,Sb₂O₃,Y₂O₃, Ta₂O₅ and the mixtures thereof.
 33. A method according toany one of claims 22 to 32, characterized in that the intermediatelayer(s) comprise(s) a mixture of at least one low index colloidalmineral oxide (n_(D) ²⁵<1.54) and at least one high index colloidalmineral oxide (n_(D) ²⁵≧1.54).
 34. A method according to claim 33,characterized in that the low index colloidal mineral oxide /high indexmineral oxide weight ratio ranges from 30/70 to 70/30.
 35. A methodaccording to claim 33 or 34, characterized in that the colloidal mineraloxide mixture is a SiO₂ and TiO₂ mixture or a SiO₂ and ZrO₂ mixture. 36.A method according to any one of claims 22 to 33, characterized in thatit comprises the step of forming two intermediate layers.
 37. A methodaccording to any one of claims 22 to 36, characterized in that theorganic glass substrate is selected amongst the diethyleneglycolbis(allylcarbonate) polymers and copolymers, homo- and copolycarbonates,poly(meth)acrylates, polythio(meth)acrylates, polyurethanes,polythiourethanes, polyepoxydes, polyepisulfides and the combinationsthereof.
 38. A method according to any one of claims 22 to 37,characterized in that the substrate has a n_(D) ²⁵ refractive indexranging from 1.55 to 1.80, preferably from 1.60 to 1.75.
 39. A methodaccording to any one of claims 22 to 38, characterized in that thepolymeric material layer is a shock resistant primer layer.
 40. A methodaccording to claim 39, characterized in that the primer is a(meth)acrylic polymer, thio(meth)acrylic polymer, polyester,polyurethane, polythiourethane based material or the combinationsthereof.
 41. A method according to any one of claims 22 to 38,characterized in that the primer material is a poly(meth)acrylic or apolyurethane latex.
 42. A method according to any one of claims 22 to38, characterized in that the polymeric material layer is ananti-abrasion coating layer.
 43. A method according to claim 42,characterized in that the anti-abrasion coating results from thehardening of a composition comprising, as main constituents, anepoxyalkoxysilane, a dialkyldialkoxysilane and colloidal silica or ahydrolyzate of such constituents.
 44. A method according to any one ofclaims 39 to 41, characterized in that it comprises the step of formingon the anti-shock primer layer, through dip coating or centrifugationand hardening, an anti-abrasion coating.
 45. A method according to anyone of claims 42 to 44, characterized in that it comprises the step offorming an anti-reflection coating on the anti-abrasion coating.